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Inflammatory chemokine transport and presentation in HEV: a remote control mechanism for monocyte recruitment to lymph nodes in inflamed tissues.

Palframan RT, Jung S, Cheng G, Weninger W, Luo Y, Dorf M, Littman DR, Rollins BJ, Zweerink H, Rot A, von Andrian UH - J. Exp. Med. (2001)

Bottom Line: MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein.Thus, MCP-1 in draining LNs was primarily derived from inflamed skin.These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.

View Article: PubMed Central - PubMed

Affiliation: Center for Blood Research, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
Interstitial fluid is constantly drained into lymph nodes (LNs) via afferent lymph vessels. This conduit enables monocyte-derived macrophages and dendritic cells to access LNs from peripheral tissues. We show that during inflammation in the skin, a second recruitment pathway is evoked that recruits large numbers of blood-borne monocytes to LNs via high endothelial venules (HEVs). Inhibition of monocyte chemoattractant protein (MCP)-1 blocked this inflammation-induced monocyte homing to LNs. MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein. Thus, MCP-1 in draining LNs was primarily derived from inflamed skin. In MCP-1(-/-) mice, intracutaneously injected MCP-1 accumulated rapidly in the draining LNs where it enhanced monocyte recruitment. Intravital microscopy showed that skin-derived MCP-1 was transported via the lymph to the luminal surface of HEVs where it triggered integrin-dependent arrest of rolling monocytes. These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.

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Rapid, sustained induction of MCP-1 in inflamed skin precipitates monocyte/macrophage accumulation in draining PLNs. (A) Time course of monocyte/macrophage recruitment to PLNs of wild-type and MCP-1−/− mice. CD11b+F4/80+ leukocytes were counted in subiliac PLNs at different times after intracutaneous injection of CFA/KLH into the ipsilateral flank. Monocyte numbers in the contralateral, noninflamed subiliac PLNs are shown for comparison. †P < 0.05; ††P < 0.01 vs. wild-type inflamed; *P < 0.01 MCP-1−/− vs. wild-type; #P < 0.05 vs. MCP-1−/− inflamed. n = 3–6 mice per group. (B) Time course of MCP-1 immunoreactivity in lysates of cutaneous sites of CFA/KLH injection (○) and the draining subiliac PLNs (•) measured by ELISA. *P < 0.05; **P < 0.01 vs. noninflamed tissue. n = 6. (C) Time course of MCP-1 mRNA expression in the CFA/KLH-inflamed subiliac PLN (•) and skin injection site (○). Fold change in MCP-1 mRNA levels over preinjection expression was measured in triplicate samples by real-time RT-PCR (TaqMan®) as described in Materials and Methods. Note that at 6 h (broken line in B and C), MCP-1 protein levels in draining PLNs were significantly increased above baseline, whereas mRNA levels were not. n = 3–6 mice per group. Symbols and bars represent mean ± SEM.
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fig1: Rapid, sustained induction of MCP-1 in inflamed skin precipitates monocyte/macrophage accumulation in draining PLNs. (A) Time course of monocyte/macrophage recruitment to PLNs of wild-type and MCP-1−/− mice. CD11b+F4/80+ leukocytes were counted in subiliac PLNs at different times after intracutaneous injection of CFA/KLH into the ipsilateral flank. Monocyte numbers in the contralateral, noninflamed subiliac PLNs are shown for comparison. †P < 0.05; ††P < 0.01 vs. wild-type inflamed; *P < 0.01 MCP-1−/− vs. wild-type; #P < 0.05 vs. MCP-1−/− inflamed. n = 3–6 mice per group. (B) Time course of MCP-1 immunoreactivity in lysates of cutaneous sites of CFA/KLH injection (○) and the draining subiliac PLNs (•) measured by ELISA. *P < 0.05; **P < 0.01 vs. noninflamed tissue. n = 6. (C) Time course of MCP-1 mRNA expression in the CFA/KLH-inflamed subiliac PLN (•) and skin injection site (○). Fold change in MCP-1 mRNA levels over preinjection expression was measured in triplicate samples by real-time RT-PCR (TaqMan®) as described in Materials and Methods. Note that at 6 h (broken line in B and C), MCP-1 protein levels in draining PLNs were significantly increased above baseline, whereas mRNA levels were not. n = 3–6 mice per group. Symbols and bars represent mean ± SEM.

Mentions: To examine monocyte recruitment to reactive PLNs and to dissect the underlying molecular mechanisms we injected CFA/KLH into the flank skin, an approach previously shown to induce a strong local inflammatory response that alters the physiology of draining PLNs (23, 24). We analyzed the number of mononuclear phagocytes (CD11b+F4/80+, reference 25) in the inflamed (i.e., ipsilateral) and the contralateral subiliac LNs (also called superficial inguinal LNs) at various times thereafter (Fig. 1 A). A small, but statistically significant increase in CD11b+F4/80+ leukocytes was seen in inflamed PLNs as early as 24 h after CFA/KLH injection. A much more dramatic rise was observed on days 3 and 7. In contrast, monocyte numbers remained low in the contralateral PLNs. This indicates that intracutaneous injection of CFA/KLH did not alter systemic monocyte behavior, but exerted its effects only at the injection site and in anatomically connected PLNs. It is possible that some of the injected CFA/KLH became lymph-borne and exerted local responses in the draining PLNs. However, as will be shown below, the dramatic effect of CFA/KLH on monocyte accumulation in draining PLNs was mainly due to continuous release of secondary mediators from inflamed skin into the lymph.


Inflammatory chemokine transport and presentation in HEV: a remote control mechanism for monocyte recruitment to lymph nodes in inflamed tissues.

Palframan RT, Jung S, Cheng G, Weninger W, Luo Y, Dorf M, Littman DR, Rollins BJ, Zweerink H, Rot A, von Andrian UH - J. Exp. Med. (2001)

Rapid, sustained induction of MCP-1 in inflamed skin precipitates monocyte/macrophage accumulation in draining PLNs. (A) Time course of monocyte/macrophage recruitment to PLNs of wild-type and MCP-1−/− mice. CD11b+F4/80+ leukocytes were counted in subiliac PLNs at different times after intracutaneous injection of CFA/KLH into the ipsilateral flank. Monocyte numbers in the contralateral, noninflamed subiliac PLNs are shown for comparison. †P < 0.05; ††P < 0.01 vs. wild-type inflamed; *P < 0.01 MCP-1−/− vs. wild-type; #P < 0.05 vs. MCP-1−/− inflamed. n = 3–6 mice per group. (B) Time course of MCP-1 immunoreactivity in lysates of cutaneous sites of CFA/KLH injection (○) and the draining subiliac PLNs (•) measured by ELISA. *P < 0.05; **P < 0.01 vs. noninflamed tissue. n = 6. (C) Time course of MCP-1 mRNA expression in the CFA/KLH-inflamed subiliac PLN (•) and skin injection site (○). Fold change in MCP-1 mRNA levels over preinjection expression was measured in triplicate samples by real-time RT-PCR (TaqMan®) as described in Materials and Methods. Note that at 6 h (broken line in B and C), MCP-1 protein levels in draining PLNs were significantly increased above baseline, whereas mRNA levels were not. n = 3–6 mice per group. Symbols and bars represent mean ± SEM.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2195988&req=5

fig1: Rapid, sustained induction of MCP-1 in inflamed skin precipitates monocyte/macrophage accumulation in draining PLNs. (A) Time course of monocyte/macrophage recruitment to PLNs of wild-type and MCP-1−/− mice. CD11b+F4/80+ leukocytes were counted in subiliac PLNs at different times after intracutaneous injection of CFA/KLH into the ipsilateral flank. Monocyte numbers in the contralateral, noninflamed subiliac PLNs are shown for comparison. †P < 0.05; ††P < 0.01 vs. wild-type inflamed; *P < 0.01 MCP-1−/− vs. wild-type; #P < 0.05 vs. MCP-1−/− inflamed. n = 3–6 mice per group. (B) Time course of MCP-1 immunoreactivity in lysates of cutaneous sites of CFA/KLH injection (○) and the draining subiliac PLNs (•) measured by ELISA. *P < 0.05; **P < 0.01 vs. noninflamed tissue. n = 6. (C) Time course of MCP-1 mRNA expression in the CFA/KLH-inflamed subiliac PLN (•) and skin injection site (○). Fold change in MCP-1 mRNA levels over preinjection expression was measured in triplicate samples by real-time RT-PCR (TaqMan®) as described in Materials and Methods. Note that at 6 h (broken line in B and C), MCP-1 protein levels in draining PLNs were significantly increased above baseline, whereas mRNA levels were not. n = 3–6 mice per group. Symbols and bars represent mean ± SEM.
Mentions: To examine monocyte recruitment to reactive PLNs and to dissect the underlying molecular mechanisms we injected CFA/KLH into the flank skin, an approach previously shown to induce a strong local inflammatory response that alters the physiology of draining PLNs (23, 24). We analyzed the number of mononuclear phagocytes (CD11b+F4/80+, reference 25) in the inflamed (i.e., ipsilateral) and the contralateral subiliac LNs (also called superficial inguinal LNs) at various times thereafter (Fig. 1 A). A small, but statistically significant increase in CD11b+F4/80+ leukocytes was seen in inflamed PLNs as early as 24 h after CFA/KLH injection. A much more dramatic rise was observed on days 3 and 7. In contrast, monocyte numbers remained low in the contralateral PLNs. This indicates that intracutaneous injection of CFA/KLH did not alter systemic monocyte behavior, but exerted its effects only at the injection site and in anatomically connected PLNs. It is possible that some of the injected CFA/KLH became lymph-borne and exerted local responses in the draining PLNs. However, as will be shown below, the dramatic effect of CFA/KLH on monocyte accumulation in draining PLNs was mainly due to continuous release of secondary mediators from inflamed skin into the lymph.

Bottom Line: MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein.Thus, MCP-1 in draining LNs was primarily derived from inflamed skin.These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.

View Article: PubMed Central - PubMed

Affiliation: Center for Blood Research, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
Interstitial fluid is constantly drained into lymph nodes (LNs) via afferent lymph vessels. This conduit enables monocyte-derived macrophages and dendritic cells to access LNs from peripheral tissues. We show that during inflammation in the skin, a second recruitment pathway is evoked that recruits large numbers of blood-borne monocytes to LNs via high endothelial venules (HEVs). Inhibition of monocyte chemoattractant protein (MCP)-1 blocked this inflammation-induced monocyte homing to LNs. MCP-1 mRNA in inflamed skin was over 100-fold upregulated and paralleled MCP-1 protein levels, whereas in draining LNs MCP-1 mRNA induction was much weaker and occurred only after a pronounced rise in MCP-1 protein. Thus, MCP-1 in draining LNs was primarily derived from inflamed skin. In MCP-1(-/-) mice, intracutaneously injected MCP-1 accumulated rapidly in the draining LNs where it enhanced monocyte recruitment. Intravital microscopy showed that skin-derived MCP-1 was transported via the lymph to the luminal surface of HEVs where it triggered integrin-dependent arrest of rolling monocytes. These findings demonstrate that inflamed peripheral tissues project their local chemokine profile to HEVs in draining LNs and thereby exert "remote control" over the composition of leukocyte populations that home to these organs from the blood.

Show MeSH
Related in: MedlinePlus